// Analytics SDK for Frontend
// 前端数据埋点 SDK

interface EventProperties {
  [key: string]: any;
}

interface DeviceInfo {
  user_agent?: string;
  screen_width?: number;
  screen_height?: number;
  language?: string;
  timezone?: string;
  platform?: string;
}

interface MetaData {
  task_id?: string | number;
  [key: string]: any;
}

interface TrackEventParams {
  event_name: string;
  properties?: EventProperties;
  device_info?: DeviceInfo;
  meta_data?: MetaData;
}

interface AnalyticsConfig {
  apiUrl: string;
  token?: string;
  userId?: number | string;
  enableAutoTrack?: boolean;
  debug?: boolean;
}

class Analytics {
  private config: AnalyticsConfig;
  private userId: number | string | null = null;
  private eventQueue: TrackEventParams[] = [];
  private isSending: boolean = false;

  constructor(config: AnalyticsConfig) {
    this.config = {
      enableAutoTrack: true,
      debug: false,
      ...config,
    };

    if (this.config.userId) {
      this.userId = this.config.userId;
    }

    // 自动收集设备信息
    if (this.config.enableAutoTrack) {
      this.initAutoTrack();
    }
  }

  /**
   * 设置用户ID
   */
  setUserId(userId: number | string) {
    this.userId = userId;
  }

  /**
   * 获取设备信息
   */
  private getDeviceInfo(): DeviceInfo {
    return {
      user_agent: navigator.userAgent,
      screen_width: window.screen.width,
      screen_height: window.screen.height,
      language: navigator.language,
      timezone: Intl.DateTimeFormat().resolvedOptions().timeZone,
      platform: navigator.platform,
    };
  }

  /**
   * 记录单个事件
   */
  async track(params: TrackEventParams): Promise<void> {
    if (!this.userId) {
      console.warn('Analytics: userId not set, event will not be tracked');
      return;
    }

    const eventData = {
      user_id: this.userId,
      event_name: params.event_name,
      properties: params.properties || {},
      device_info: {
        ...this.getDeviceInfo(),
        ...params.device_info,
      },
      meta_data: {
        timestamp: Date.now(),
        ...params.meta_data,
      },
    };

    if (this.config.debug) {
      console.log('Analytics Track:', eventData);
    }

    try {
      const response = await fetch(`${this.config.apiUrl}/track`, {
        method: 'POST',
        headers: {
          'Content-Type': 'application/json',
          ...(this.config.token && { Authorization: `Bearer ${this.config.token}` }),
        },
        body: JSON.stringify(eventData),
      });

      if (!response.ok) {
        throw new Error(`Failed to track event: ${response.statusText}`);
      }

      if (this.config.debug) {
        console.log('Analytics: Event tracked successfully');
      }
    } catch (error) {
      console.error('Analytics: Failed to track event', error);
      // 失败时加入队列，稍后重试
      this.eventQueue.push(params);
    }
  }

  /**
   * 批量记录事件
   */
  async trackBatch(events: TrackEventParams[]): Promise<void> {
    if (!this.userId) {
      console.warn('Analytics: userId not set, events will not be tracked');
      return;
    }

    const batchData = {
      events: events.map((params) => ({
        user_id: this.userId,
        event_name: params.event_name,
        properties: params.properties || {},
        device_info: {
          ...this.getDeviceInfo(),
          ...params.device_info,
        },
        meta_data: {
          timestamp: Date.now(),
          ...params.meta_data,
        },
      })),
    };

    if (this.config.debug) {
      console.log('Analytics Track Batch:', batchData);
    }

    try {
      const response = await fetch(`${this.config.apiUrl}/track/batch`, {
        method: 'POST',
        headers: {
          'Content-Type': 'application/json',
          ...(this.config.token && { Authorization: `Bearer ${this.config.token}` }),
        },
        body: JSON.stringify(batchData),
      });

      if (!response.ok) {
        throw new Error(`Failed to track batch events: ${response.statusText}`);
      }

      if (this.config.debug) {
        console.log('Analytics: Batch events tracked successfully');
      }
    } catch (error) {
      console.error('Analytics: Failed to track batch events', error);
    }
  }

  /**
   * 页面浏览事件
   */
  trackPageView(pageName?: string) {
    this.track({
      event_name: 'page_view',
      properties: {
        page_url: window.location.href,
        page_title: document.title,
        page_name: pageName || document.title,
        referrer: document.referrer,
      },
    });
  }

  /**
   * 点击事件
   */
  trackClick(elementName: string, properties?: EventProperties) {
    this.track({
      event_name: 'click',
      properties: {
        element_name: elementName,
        page_url: window.location.href,
        ...properties,
      },
    });
  }

  /**
   * 表单提交事件
   */
  trackFormSubmit(formName: string, properties?: EventProperties) {
    this.track({
      event_name: 'form_submit',
      properties: {
        form_name: formName,
        page_url: window.location.href,
        ...properties,
      },
    });
  }

  /**
   * 任务相关事件
   */
  trackTask(taskId: string | number, action: string, properties?: EventProperties) {
    this.track({
      event_name: `task_${action}`,
      properties: {
        action,
        ...properties,
      },
      meta_data: {
        task_id: taskId,
      },
    });
  }

  /**
   * 初始化自动埋点
   */
  private initAutoTrack() {
    // 页面加载完成时记录
    if (document.readyState === 'complete') {
      this.trackPageView();
    } else {
      window.addEventListener('load', () => this.trackPageView());
    }

    // 页面离开前发送队列中的事件
    window.addEventListener('beforeunload', () => {
      if (this.eventQueue.length > 0) {
        this.flushQueue();
      }
    });

    // 页面可见性变化
    document.addEventListener('visibilitychange', () => {
      if (document.hidden && this.eventQueue.length > 0) {
        this.flushQueue();
      }
    });
  }

  /**
   * 刷新队列中的事件
   */
  private flushQueue() {
    if (this.isSending || this.eventQueue.length === 0) {
      return;
    }

    this.isSending = true;
    const eventsToSend = [...this.eventQueue];
    this.eventQueue = [];

    this.trackBatch(eventsToSend).finally(() => {
      this.isSending = false;
    });
  }

  /**
   * 手动刷新队列
   */
  flush() {
    this.flushQueue();
  }
}

// 导出单例实例
let analyticsInstance: Analytics | null = null;

export function initAnalytics(config: AnalyticsConfig): Analytics {
  analyticsInstance = new Analytics(config);
  return analyticsInstance;
}

export function getAnalytics(): Analytics {
  if (!analyticsInstance) {
    throw new Error('Analytics not initialized. Call initAnalytics first.');
  }
  return analyticsInstance;
}

export default Analytics;